[1] Univ N Carolina, Dept Biol, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Dept Genet, Chapel Hill, NC 27599 USA
[3] Univ N Carolina, Carolina Ctr Genome Sci, Chapel Hill, NC 27599 USA
[4] Univ N Carolina, Lineberger Comprehens Canc Ctr, Chapel Hill, NC 27599 USA